git-for-each-ref: improve the documentation on scripting modes

When reading the synopsis for git-for-each-ref it is easy to miss
the obvious power of --shell and family.  Call this feature out in
the primary paragragh.  Also add more description to the examples
to indicate which features we are demonstrating.  Finally add a
very simple eval based example in addition to the very complex one
to give a gentler introduction.

Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/Documentation/git-for-each-ref.txt b/Documentation/git-for-each-ref.txt
index 6649f795e8714d9f084a5f4db18bf3a1d405d46a..d5fdcef8d9e60d061ed83a8388ad1d3d0a47e6a5 100644 (file)
--- a/Documentation/git-for-each-ref.txt
+++ b/Documentation/git-for-each-ref.txt
@@ -17,7 +17,7 @@ according to the given `<format>`, after sorting them according
 to the given set of `<key>`s.  If `<max>` is given, stop after
 showing that many refs.  The interporated values in `<format>`
 can optionally be quoted as string literals in the specified
-host language.
+host language allowing their direct evaluation in that language.
 
 OPTIONS
 -------
@@ -97,7 +97,8 @@ returns an empty string instead.
 EXAMPLES
 --------
 
-Show the most recent 3 tagged commits::
+An example directly producing formatted text.  Show the most recent
+3 tagged commits::
 
 ------------
 #!/bin/sh
@@ -112,7 +113,23 @@ Ref: %(*refname)
 ' 'refs/tags'
 ------------
 
-A bit more elaborate report on tags::
+
+A simple example showing the use of shell eval on the output,
+demonstrating the use of --shell.  List the prefixes of all heads::
+------------
+#!/bin/sh
+
+git-for-each-ref --shell --format="ref=%(refname)" refs/heads | \
+while read entry
+do
+       eval "$entry"
+       echo `dirname $ref`
+done
+------------
+
+
+A bit more elaborate report on tags, demonstrating that the format
+may be an entire script::
 ------------
 #!/bin/sh
 
@@ -156,7 +173,7 @@ Its message reads as:
        fi
 '
 
-eval=`git-for-each-ref -s --format="$fmt" \
+eval=`git-for-each-ref --shell --format="$fmt" \
        --sort='*objecttype' \
        --sort=-taggerdate \
        refs/tags`